Electrode arrangements for facsimile recorders



April 1952 w. H. TRIBBLE ELECTRODE ARRANGEMENT 'FOR FACSIMILE RECORDERS Filed May 2, 1947 INVENTOR. W/LA/A/V f/ 72 /5545 Patented Apr. 1, 1952 ELECTRODE ARRANGEMENTS FOR FACSIMILE RECORDERS William H. Tribble, East Moriches, N. Y., assignor, by mesne assignments, to Jefferson Standard Broadcasting Company, a corporation of North Carolina Application May 2, 1947, Serial N 0. 745,609

This invention relates to electrical signalling systems and more particularly to a recording electrode of helical form for use with facsimile recorders and the like to effect electrolytic recording.

In my abandoned co-pending application Serial No. 745,608, filed Ma 2, 1947, and entitled Facsimile Recorders, I disclosed a flat type electrode having dual recording edges for use in electrolytic recording to reproduce a subject matter of substantially uniform density and improved definition, because of its ability to position itself automatically in response to the uneven surface of the electrolytic recording paper used.

In one method of facsimile practice, the recording is effected by bringing a flat or wire type electrode into operable association with an electrode of helical form affixed to a, rotatable drum. It is a well known fact that when the actual recording is effected by the breakdown of the electrolytic recording paper, as a result of .the passage of electric current through, it causes the paper to give off a considerable amount of moisture. This moisture condenses, largely, upon the periphery of the drum carrying the helical form electrode and it even adheres to that drum despite its rotation. The rotating drum comes in contact with or in close proximity to the recording paper before the actual recording is effected and therefore transmits moisture, deposited as a result of the previous recording, to the recording paper. In order to obtain a recorded subject having maximum definition and uniformity the moisture given off by the passage of electric current through the paper should remain on the paper for a certain predetermined time dependent upon the particular characteristics of the paper used. It is clear from the foregoing that the surface of the drum coming in contact with the paper immediately after the effecting of the recording, collects such a large quantity of moisture that the obtaining of a recorded subject matter of uniform density and good definition is impossible because of the collection of condensation on the drum.

After the recording is continued for a relatively short period, the moisture retaining characteristic of the drum results in the recording paper being in a supersaturated condition at the time actual recording takes place. This condition is another inherent characteristic of facsimile recorders of the prior art and also contributes in the production of a recorded subject matter lacking in uniform density and detail.

It is a principal object of this invention to provide an electrode of helical form for electrolytic recording wherein the electrode and parts associ- 4 Claims. (Cl. 346101) ated therewith are substantially incapable of collecting a considerable amount of moisture as a result of the recording operation.

It is another object of this invention to provide a rotatably mounted electrode of helical form for use in electrolytic recording, arranged to effect the recording and simultaneously to aid in eliminating excess moisture from further contact with the recording paper.

It is a further object of this invention to provide an electrode of helical form for use in facsimile recording wherein the helical pitch of the electrode or the actual recording time per revolution of that electrode is adjustable.

It is a still further object of this invention to provide mounting means for a rotatable electrode to be used in the facsimile recording wherein said means insure that the electrode associated with said rotatable electrode is always substantially equidistant from the arc of travel of said rotatable electrode.

A feature of the invention relates to a rotary brush arrangement for cleaning a helical strip recording electrode, the brush being mounted for convenient movement towards and away from the strip electrode.

Another feature of this invention relates to the series of discs for mounting the rotatable spiral form electrode in that means are provided to maintain that electrode and the associated recording electrode in a substantially fixed spaced relationship irrespective of the percentage of time during which actual recording is effected.

A further feature relates to a helical strip or wire recording electrode which is provided with a plurality of spaced supports adjustable along the rotary shaft carrying the electrode to enable the electrode to be adjusted to correspond with the particular width of the sheet upon which recording is to take place.

A still further feature of this invention relates to the novel organization and arrangement of parts which cooperate to produce an improved electrode of the rotatable type for recording purposes wherein the subject matter recorded is of well-defined detail and of uniform density.

Other objects, features and advantages not particularly enumerated will be apparent to those skilled in the art from the following description taken in connection with the accompanying drawing.

In the drawing,

Fig. 1 is an isometric view showing the principles of this invention;

Fig. 1A is an elevation view of a portion of Fig. 1;

Fig. 1B shows a portion of the electrode support element shown in Fig. 1;

A record receiving paper blank H is passed between the helical electrode and the cooperating flat strip type electrode [2 which is preferably formed and arranged as described in my co-pending application referred to above. This electrode consists of a flat metal strip I2a of thin gauge metal stock clamped along its median length between bars I21), 120, which extend beyond the ends of the strip in and are slidably mounted in suitable supports (not shown). Bristle brush E3 of cylindrical form is rotatably mountedparallel to assembly l so that the entire periphery of that assembly is brushed during each of its rotations. Brush I3 is positioned by'arm M adapted to receive therein the shaft l! which carries the brush. Arm Hi is pivotally mounted on pin l5. It is obvious that brush I3 is held against the periphery of assembly H) by the pressure exerted by spring l6 andthat rotation of assembly It tends to rotate that brush by reason of the frictional contact between the brush and the helical electrode. Brush i3 is swingable around pin l in a counterclockwise direction by merely pulling brush 13 away from assembly HI against the pressure of spring It. A similar arm, spring and pin (not shown) are associated with the opposite end of the shaft l1.

Electrode assembly IE! is rotatably mounted on the chassis of the recorder and motor driven in onedirection only in" any conventional and wellknown manner. The assembly comprises the rotatably mounted shaft l8, discs l923 inclusive, secured to shaft I3 by any suitably adjustable means such as set screws; and the helical metallic electrode support member 24 fitted onto the periphery of each disc; and wire electrode 25 secured'in a grooveof member 24. While this assembly is shown as including five discs Iii-23 inclusive, the number of such discs can be varied tov meet the requirements of the particular situation; It is clear from the drawing that the discs, when loosened, are slidable along shaft l8 and therefore the distance between discs I9 and 23 is adjustable, thus enabling the effective recording width of the helical electrode to be correlated with thewidth of the sheet H. This offers particular advantage in that a single assembly can be 'used to eifect recording on paper of different width. This represents a distinct advantage over the recording practice of the prior art because each of those rotatable electrodes is capable of effecting recording only on paper of a certain width and does not permit adjustability of the recording length.

Member 24 is of metal and substantially rectangular in cross section, having suitable bendable characteristics to enable it to be formed into a spiral. Member 24 is'attached to each disc by any suitable means such as, for example, screws 24a or solder. As will be seen from the subsequent description, it facilitates the full utilization of a novel operational characteristic of this" invention if slots 24b, 220, are provided in electrode support member 24,. These slots are of .suflicient length to permit the helical member 24 to be bodily adjusted in a direction transverse to the. associated discs when the screws 24a are loosened.

Fig. 1B shows the relation between one of the discs, for example disc l9, and the member 24. This figure shows the member 24 with two slots 24b, 240, through which the screws 24a pass for attachment to the disc [9.

A grooved or square-walled trough (best shown in Figs. 2 and3) is formed in helical member 24 to receive the wire electrode 25, which is preferably of rectangular cross section. The rectangular cross section of electrode 25 is a particular advantage where it is desired that the recorded subject matter be of well-defined detail and of uniform density. When this wire is subject to the wear caused by normal operation, the width of its effective recording surface is unchanged and the characteristics of the recorded subject matter are therefore unaffected by the normal wear of operation. If wire 25 were of round cross section,..its efiective recording area, after continued wear, would change.

After the discs i923 are assembled on shaft 18, the grooved helical electrode support member 24 is attached to the discsl923. .Wire electrode 25 is then placed in the groove of member 24 and held at the desired tension by screw members 26 and 21 carried by the said discs I9 and 23 respectively. A convenient and simple means for adjusting and maintaining the desired tension is best shown in Fig. 1A. Since screw members 2'6 and 2"! are identical, only the member 26 is shown in that figure. That member comprises the integral knurled head and threaded body portion. 25a and 26b respectively and knurled nut 25cthreaded to be screwed onto the body portion 26b.

screwed into abutment with disc IS. A hole is provided in the body portion of member 26 to receive the wire electrode 25.

To secure electrode 25 at the proper tension is a simple matter; for example, one end is ex'- tended through the hole 26b in the shank of member 25 and wrapped therearound several times, it is then placed in the groove of member 24 and the other end is similarly anchored to a device 21 "which is structurally the same-as device 26. Upon rotation of knurled head 26a the tension of wire 25 is either increased or decreased depending upon the direction of that rotation. When the proper tension is acquired, head 260 of member 25 is screwed into abutment with disc l9 which insures the maintenance of that tension at substantially the same value.

Since member 2 5 is attached to the peripheries of the discs and because of the inherent nature of the recording process (i. e. recording is efiected during only approximately 350 to 358 of each rotation oi assembly l0) that member is not always interposed between the discs and the recording paper and a bumping or tearing of thepaper is very likely when it comes into contact with the paper and when it passes out of contact with the paper. Provisions are made to eliminate this bumping and tearing caused by the rotation of the assembly iii. These provisions are-best shown in Figs. 2 and 3.

Screw member 26 is fixed relative to disc is when nut 250 is in the dotted position, i. e., v

and 29 are identical in form and abut against spiral m mber 24 on opposite sides of it and at opposite ends. It follows that the gradients established by members 28 and 29 are of equal and opposite slope. The assembly I0 is rotated only in the direction indicated by th arrow on disc [9 and effects actual recording during less than 360 (for example 350 or 358) of its r0- tation. This, in the absence of member 28 and member 29, would cause recording paper H to be pressed against th peripheries of discs [9-43 by the electrode 52 when no recording is being effected.

The member 28 and member 29 prevent this undesirable efiect by allowing the paper at the beginning of each transverse scanned line, to ride on the rising member 23 when the beginning of each transverse scanning line is being approached, and to ride on the member 29 imme diately after the scanned line end has been reached. It is readily seen that the members 28 and 29 may be formed to extend any desired distance along the periphery of the disc associated therewith and thereby permit recording during any desired portion of time however small or large without any bumping or tearing effect whatsoever. If desired, in the place of the members 28 and 29, the discs l9 and 23 may be made of slightly larger diameter than the other discs and recessed to receive member 24 so that its outermost side is flush with the periphery of the discs. However this latter modification increases the cost of fabrication since all the discs i923 cannot be made identical.

A novel and very important advantage of this invention is the fact that the pitch of the helical electrode support member and the wir electrode is easily changed. That is to say, that they are readily positioned on the disc peripheries to effect recording only during a certain predetermined angular portion of the rotation of assembly ii). To change his pitch, screw member 26 is loosened and the tension on wire electrode 25 is relieved, the connections of the member 24 to the discs l9-2 2 are loosened, those discs are then loosened and rotated to the desired new position and re-tightened on shaft [8, then, as described above, the tension of wire electrode 25 is adjusted properly. The slotted portions of member 24 engaged by the screw fastening that member to the disc allows the movement of member 24 relative to the disc to which it is fastened and therefore permits a change in the pitch of that member.

While there have been here described preferred embodiments of this invention, it is understood that various changes and modifications may be made therein without departing from the scope of the invention.

What is claimed is:

1. In a dynamically balanced rotatable electrode assembly having discs as supporting members, an electrode of the helical type mounted on the peripheries of each of said discs, said electrode being so mounted that it is supported on the peripheries of said discs and effects recording over an are less than 360 during each rotation of said assembly, oppositely sloped riser strips adjacent to said electrode and affixed respectively to the periphery of the outermost discs of said assembly, said strips permitting a transition from the recording condition to the non-recording condition and without any tearing or substantial bumping of the recording paper.

2. A rotatable helical platen assembly for facsimile recorders and the like, comprising a rotatable shaft, a plurality of spaced discs mounted on said shaft and releasably fastened thereto for independent sliding adjustment on said shaft and independent rotational adjustment around said shaft, a helical member releasably fastened to the edges of said discs, means defining a helical groove along the length of said member and a Wire electrode rectangular in cross section extending along said groove, and means to anchor the ends of said wire electrode to maintain it in a fixed relation within said groove.

3. A platen assembly according to claim 2 in which the last-mentioned means includes adjustable screw members affixed respectively to the end discs, each of said screw members having means to receive and retain one end of said wire and to mainta n it under a predetermined tension.

4. A marking electrode assembly for use in electrolytic recording machines of the type having a helically ridged platen and a cooperating transverse striker bar, said platen including a shaft rotatably mounted on the chassis of the recording machine, a plurality of discs fixedly mounted on said shaft, a helically formed electrode support member secured to the peripheries of said discs, said support member having means defining a helical groove, a wire electrode located in said groove, screw and tension means associated with the outermost one of said discs for holding and adjusting the tension of said wire electrode, said support member extending transversely across the edges of each of said discs and the region of said support member adjacent each disc being provided with elongated slots, and screw-fastening means passing through each slot into the edge of the associated disc, said slots being of sufficient length to enable the pitch of said member to be adjusted when said screws are unloosened.

WILLIAM H. TRIBBLE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 789,984 Macklind May 16, 1905 952,144 sauer Mar. 15, 1910 1,909,142 Zworykin et al May 16, 1933 2,104,109 Young Jan. 4, 1938 2,131,547 Artzt Sept. 27, 1938 2,202,855 Hogan et a1 June 4, 1940 2,336,909 Wise Dec. 14, 1943 2,384,722 Blain Sept. 11, 1945 2,389,021 Blain Nov. 13, 1945 2,421,781 Gibbs June 10, 1947 2,434,531 Wilson et al Jan. 13, 1948 2,480,890 Tribble Sept. 6, 1949 2,511,704 Finch et a1 June 13, 1950 

